What is the function of the iris?

The function of the iris primarily revolves around regulating the amount of light that enters the eye. The iris is the colored part of the eye and consists of muscles that can constrict or dilate the pupil. When the light is bright, the muscles of the iris constrict to make the pupil smaller, allowing less light to enter; conversely, in low-light conditions, the muscles relax to dilate the pupil, allowing more light in. This function helps protect the retina from excessive light and enhances visual acuity by optimizing the amount of light that reaches the photoreceptors in the retina. Understanding this function is essential for grasping how the eye adjusts to varying lighting conditions, which is critical in maintaining clear vision.